Downy Mildew of Cucurbits
Pseudoperonospora cubensis
Cucurbitsoomycete
A fast-spreading, humidity-driven disease producing purple-gray fungal down on leaf undersides.
Symptoms
Angular yellow leaf spots bounded by veins, with purple-gray fungal down developing on the underside in humid weather, followed by rapid defoliation.
Favorable conditions
- •High humidity and extended leaf wetness
- •Rapid regional spread by wind-blown spores
Management
- 1Apply a fungicide program timed with regional disease forecasting
- 2Plant resistant varieties
- 3Avoid overhead irrigation
- 4Improve canopy airflow
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